1. Neighbor discovery to support direct communication in ITS
draft-yan-its-nd-01.txt
Zhiwei Yan & Jong-Hyouk Lee

2. Neighbor discovery in ITS
Discover the neighbor vehicle and the nearby service
Learn the link-layer address of the selected neighbor vehicle
In the dynamic and fragmentation-possible environment--VANET
Assumptions:
Name: vehicle SHOULD have a temporary name which is related to location
Address: vehicle SHOULD have a global IP address which is more stable

3. ITS Network Architecture
May be out the scope of this draft
Logically:
Internet
Router
IP Prefix
*WSA: IP prefix+name+…
RSU1
RSU2
Local name1
Local name2
Vehicle1
Vehicle1
Vehicle1
Address: IP Prefix
Name: local name1
Address: IP Prefix
Name: local name2
Address: IP Prefix
Name: local name1
Name: local name2

4. Why mDNS (Multicast DNS)?
Suitable for the infrastructure-less environment
VANET
For service discovery
Discovery the named service and named vehicle
Standardized protocol
ST-RFC6762, based on DNS
Neighbor vehicles with the same prefix are ON THE SAME LINK

5. ND based on mDNS---- Ad-hoc based
Different modes can be used in different scenarios:
One-shot Multicast DNS Query
E.g., Locate the specific service
Continuous Multicast DNS Query
E.g., Locate the nearby vehicles which are moving
Multiple Questions per Query: Locate multiple services/vehicles simultaneously
Multiple Questions Multicast Responses: update the caches of receivers
Multiple Questions Unicast Responses: new vehicle joins

6. ND based on mDNS----RSU based
Vehicles MAY have direct connection with RSU
RSU is a local DNS server
RSU maintains the registered vehicle/services
or acts as a relay/proxy:
Direct Unicast Queries to Port 5353 or
Legacy Unicast DNS

7. ND based on mDNS Probing and Announcing on Startup
A vehicle starts up, wakes up from stalls, topology changes (after configuration of the name and address):
Probe the availability of the service it announced
Then, announce the service and its existence
Unsolicited multicast DNS response containing, in the Answer Section, all of its service and name and address……
Update the information actively if there is any change

8. ND based on mDNS Goodbay~
A vehicle will arrive at its destination, stall temporarily or shut down its camera…
Announce the service suspending and its inexistence
Unsolicited multicast DNS response packet, giving the same RRs (containing its name and address), but TTL of zero

9. Signaling messages TBD: To piggyback link-layer address
To include Geo-information ….
OR:
mDNS service discovery + NDP
mDNS service discovery + Others
Extension of mDNS RR

10. Security considerations
DNS traffic reduction and flooding avoidance
With mDNS schemes
Known-Answer Suppression
Multipacket Known-Answer Suppression
Duplicate Question Suppression
Duplicate Answer Suppression
Origination: DNS message Source Address Check
DNS message tampering avoidance
With DNSSEC, IPsec ……

11. Thank you for your attention~